JPH11348307A - Ink jet recording device - Google Patents

Abstract

(57) [Object] To provide an ink jet recording apparatus capable of efficiently discharging fine bubbles adhered to the inner surface of an ink supply path of a manifold by purging processing. An ink supply path for supplying an ink liquid in an ink cartridge to an ejection channel of an ink jet head is formed in a manifold, and the ink supply path is connected to an ink cartridge. Part 44 and an enlarged part 45 extending outward from the connection part 44 and surrounding the ink supply port of the ejection channel.
It is composed of A turbulence generating portion is formed in the connecting portion 44 by a columnar crossing member 44a crossing the connecting portion 44, and the ink flow introduced into the ink supply path 43 at the time of the purging process is changed by the crossing member 44a. The turbulent flow is caused by the presence of the ink, so that the ink flow velocity near the inner surface of the ink supply path 43 increases, and the microbubbles attached to the inner surface of the ink supply path 43 are discharged together with the ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus in which an ink supply source and an ink jet head are connected to each other by a manifold having an ink supply path, and in particular, discharge of air bubbles existing in the ink supply path in a purge process. The present invention relates to an ink jet recording apparatus having excellent properties.

[0002]

2. Description of the Related Art An ink jet recording apparatus such as an ink jet printer records characters and images on a recording medium such as paper by ejecting ink droplets from an ink jet head mounted on a carriage. An ink cartridge filled with ink is exchangeably attached to the head via a manifold having an ink supply path.

An ink-jet head has a large number of ink storage chambers provided in an aligned state, and an electromechanical conversion element or an electro-thermal conversion element for ejecting ink stored in each ink storage chamber as ink droplets from a nozzle at a tip end. The ink in the ink cartridge is supplied to each ink storage chamber through an ink supply path of the manifold, and is ejected from the ink storage chamber by the actuator as ink droplets.

[0004] By the way, the ink filled in the ink cartridge usually has a considerable amount of air dissolved therein, and when replacing the ink cartridge, a certain amount of air is discharged from the connection portion between the ink cartridge and the manifold. The air enters the ink supply path of the manifold, so that such air is taken as fine bubbles into the ink storage chamber of the inkjet head together with the ink, thereby causing a printing failure due to non-ejection of ink droplets.

Therefore, conventionally, a purging process has been generally performed in which the air in the manifold is discharged to the outside together with the ink by sucking the ink from the nozzle side of the ink jet head at the time of replacing the ink cartridge or periodically after replacing the ink cartridge. It is being done.

[0006]

However, if the air present in the ink supply path of the manifold is only floating in the ink supply path as microbubbles, it is easy to discharge to the outside by a purge process. There are many small bubbles that adhere to the inner surface of the ink supply path as micro bubbles at places where ink is likely to bubble, such as a part where the shape of the path changes, and the micro bubbles that adhere to the inner surface of the ink supply path are Even if the purging process described above is performed,
Since there is almost no flow velocity in the part along the inner surface, it is impossible at present to discharge sufficiently.

[0007] As described above, the microbubbles which cannot be discharged by the purging process and remain in the ink supply path grow into large bubbles with the passage of time, and eventually block the ink storage chamber. Therefore, even if the purging process is performed, a printing failure often occurs again in a short time, and there is a problem that the purging process must be performed frequently during use of the inkjet recording apparatus.

Accordingly, an object of the present invention is to provide an ink jet recording apparatus capable of efficiently discharging microbubbles attached to the inner surface of an ink supply path of a manifold by purging.

[0009]

According to a first aspect of the present invention, there is provided an ink jet recording apparatus comprising: a plurality of ink storage chambers for storing ink to be ejected arranged in an aligned state; An ink jet recording apparatus comprising: a head; an ink supply head that interconnects the ink jet head and an ink supply source; and a manifold having an ink supply path for supplying ink from the ink supply source to the plurality of aligned ink storage chambers. The ink supply path has a connection portion connected to the ink supply source, and an enlarged portion extending outward from the connection portion and surrounding the ink supply ports of the plurality of aligned ink storage chambers, A turbulence generator that generates turbulence in the ink introduced from the ink supply source into the ink supply path, To have.

In the ink jet recording apparatus constructed as described above, when ink is introduced from the ink supply source into the ink supply path of the manifold by the purging process, the turbulent flow generating section formed at the connection of the ink supply path is formed. By
Since the ink flow in the ink supply path becomes turbulent, the ink flow velocity near the inner surface of the ink supply path increases, and the microbubbles attached to the inner surface are easily peeled off and discharged together with the ink.

In particular, when the turbulence generating portion is formed by a cross member that crosses the connecting portion as in the ink jet recording apparatus according to the second aspect of the present invention, the purging process has a simple structure. In this case, the ink flow velocity near the inner surface of the ink supply path can be increased, and bubbles can be discharged.

Further, as in the ink jet recording apparatus according to the third aspect of the present invention, the turbulent flow generating portion is formed by a spiral projection spirally protruding from the inner surface of the ink supply path, thereby forming a spiral in the ink flow direction. When the vortex is generated, a high flow velocity is formed along the inner surface of the ink supply path, and the bubbles can be effectively separated and discharged.

Particularly, in the ink jet recording apparatus according to the present invention, the ink supply path is formed so as to extend substantially vertically downward from the ink supply source to the ink jet head. Since the air bubbles generated at the time of rest and the like are likely to float, even if they are grown, the ink storage chamber of the inkjet head is hardly closed in a short time, and is easily discharged even by turbulence or eddy current. According to the third aspect of the present invention, the ink supply path is set to be substantially vertical, so that the shape of the spiral projection is counterclockwise when the direction of the vortex generated thereby is used in the northern hemisphere. When used, it can be clockwise so that Coriolis forces can work effectively to generate an effective vortex.

According to another aspect of the present invention, there is provided an ink jet recording apparatus comprising: a plurality of ink storage chambers for storing ink to be ejected; A manifold having an ink supply path for supplying ink from the ink supply source to the plurality of aligned ink storage chambers, wherein the inkjet head and the ink supply source are interconnected, and a manifold opposite to the inkjet head. An ink-jet recording apparatus comprising: a suction unit detachably connected to the ink supply source and filling the plurality of the ink storage chambers through the manifold with the ink from the ink supply source.
The ink supply path includes a connection portion connected to the ink supply source, and an enlarged portion extending outward from the connection portion and surrounding the ink supply ports of the plurality of aligned ink storage chambers, A turbulence generating unit is provided in the connection unit for generating turbulence in the ink introduced from the ink supply source into the ink supply path by suction by the suction unit.

In the ink jet recording apparatus constructed as described above, the suction means is connected to the side of the ink jet head opposite to the manifold, and the ink is supplied from the ink supply source to the plurality of ink storage chambers through the manifold to purge the ink. In the process, when the ink is introduced from the ink supply source into the ink supply path of the manifold, the turbulence generating section formed at the connection part of the ink supply path causes the ink flow in the ink supply path to become turbulent. Therefore, the ink flow velocity near the inner surface of the ink supply path increases, and the microbubbles attached to the inner surface are easily peeled off and discharged together with the ink.

[0016]

Embodiments will be described below with reference to the drawings. As shown in FIG. 1, the inkjet recording apparatus 1 ejects four color inks of cyan, magenta, yellow, and black onto a printing paper P as a recording medium to perform printing or image formation (hereinafter, image formation). And a head unit 30 provided with four ink jet heads 31 and four ink cartridges 50 serving as ink supply sources for supplying ink liquids of four colors to the respective ink jet heads 31. Are mounted on the carriage 11.

A platen roller 18 is provided below the head unit 30 so as to be rotatable in parallel to the reciprocating direction of the platen roller 18 so as to face the lower surface of the ink jet head 31. A printing unit is constituted by 31.

The carriage 11 has an ink jet head 31 having both ends supported by a frame (not shown).
Slidably supported by a carriage shaft 12 and a guide plate 13 extending in the reciprocating direction of the
It is connected to a belt 16 spanned between 4 and 15,
When the pulley 14 is driven to rotate by the motor 17, the carriage 11 reciprocates linearly.

The printing paper P is inserted between the ink jet head 31 and the platen roller 18, where it is printed, and then discharged in the direction indicated by the arrow in FIG. In FIG. 1, illustration of the paper feed mechanism for the printing paper P is omitted.

As shown in FIG. 2, the head unit 30 is provided with four manifolds 40 for connecting the respective ink cartridges 50 to the respective ink jet heads 31.
Reference numeral 0 denotes an ink cartridge that is fixed to one end so as to cover the upper surface of the inkjet head 31, and that the ink cartridge 50 is detachably connected to the other end via a joint member 50a. In addition, as shown in the figure, the ink cartridge 50 has a first ink chamber 51 for storing a porous ink absorbing material such as polyurethane foam.
And a second ink chamber 52 communicating with the first ink chamber 51.
The ink liquid flows from the ink absorbing material impregnated with the ink liquid in the first ink chamber 51 to the manifold 40 from the ink supply port 53 through the communication hole 51a and the second ink chamber 52. Supplied. The ink supply port 53 is provided with a mesh filter 53a.

As shown in FIG. 2, the ink jet head 31 includes an actuator 32 made of piezoelectric ceramic for ejecting an ink liquid, and a nozzle plate 34 mounted on one end surface of the actuator 32. 32, a plurality of ejection channels 33 as ink storage chambers extending from one end surface serving as a lower surface to the other end surface serving as an upper surface are formed in a state of being arranged in two rows. A large number of nozzle holes (not shown) are formed corresponding to the injection ports of each injection channel 33 opened at one end surface of the nozzle 32.

Each of the ejection channels 33 formed in the actuator 32 has an ink supply port 33 of each ejection channel 33 opened on the other end surface of the actuator 32.
From a, the ink liquid in the ink cartridge 50 is introduced through an ink supply path 43 formed in the manifold 40, and the volume of the ejection channel 33 is changed by deforming the actuator 32. Thus, the ejection of the ink liquid from the ejection channel 33 and the introduction of the ink liquid into the ejection channel 33 are performed. That is, when the volume of the ejection channel 33 decreases, the ink liquid stored in the ejection channel 33 is ejected from the nozzle holes of the nozzle plate 34 as ink droplets, and the volume of the ejection channel 33 expands to the original state. At times, an ink liquid is introduced into the ejection channel 33.

As shown in FIG. 1, an ink jet head 31 set on the side of the platen roller 18 is provided.
In the reset state position, the ink suction device 21 as a suction unit for performing a purging process, the wiper device 26 for wiping the nozzle plate 34 of the inkjet head 31, and the inkjet head 31 when printing is not performed.
And a protective cap device 27 that covers the nozzle plate 34 and prevents the nozzle holes from drying, and is provided at the forced ejection position set on the opposite side of the reset state position across the platen roller 18. In order to prevent clogging of the nozzle plate 34 by periodically forcibly ejecting the ink from the inkjet head 31, an ink holding member 28 for absorbing and holding the forcibly ejected ink is provided. The ink suction device 21, the wiper device 26, and the protective cap device 27
The ink holding member 28 constitutes a recovery maintaining unit for recovering and maintaining the ejection function of the inkjet head 31.

The ink suction device 21 includes a suction pump 2
2, a suction unit 23, a waste ink tank 24, and a cam 25. The suction pump 22 and the suction unit 23 are driven by a power transmission mechanism (not shown) via the cam 25.

When the purging process is performed using the ink suction device 21, the suction unit 23 is
While the nozzle plate 34 is covered, the suction pump 2
2, a negative pressure is generated, and a defective ink liquid including air bubbles and the like in the ink supply path 43 and the ejection channel 33 of the manifold 40 is sucked, so that the ink cartridge 5
The ink jet head 31 is recovered by introducing a new ink liquid into the ejection channel 33 from zero. The sucked defective ink liquid is sent to the waste ink tank 24. After the ink cartridge 50 is replaced, the same operation is performed when the ink liquid is introduced into the inkjet head 31 from the new ink cartridge 50 (initial introduction).

The manifold 40 is shown in FIGS.
As shown in the figure, a frame 41 and a main body 42 disposed inside the frame 41 and partially connected to the inner surface of the frame 41.
The frame 41 has a pair of fixing pieces 41a fixed to the side surface on the other end side of the ink jet head 31 with an adhesive, and positioning when the manifold 40 is fixed to the ink jet head 31. And a pair of positioning pieces 41b are connected to each other. In addition,
By filling the space S formed between the frame 41 and the main body 42 with an adhesive in a state where the fixing piece 41a and the ink jet head 31 are fixed with the adhesive, the other end surface of the ink jet head 31 Is prevented from leaking.

An ink supply path 43 for supplying the ink liquid in the ink cartridge 50 to a plurality of ejection channels 33 formed in the ink jet head 31 is formed in the main body section 42.
Is a small-diameter connection portion 44 having an ink inlet 43a connected to the ink cartridge 50;
And an ink outlet 43b which expands in a tapered shape from outside to surround the ink supply port 33a of the ejection channel 33.
And an enlarged portion 45 having Note that a mesh filter 40 is provided at the ink inlet 43a of the connection portion 44.
a is attached.

The connection portion 44 is located at substantially the center of a channel row constituted by a plurality of ejection channels 33, and the enlarged portion 45 is connected to the ejection channel formed on the ink jet head 31 from the connection portion 44. It extends almost symmetrically toward the end of the row.

As shown in FIGS. 7A and 7B, a turbulent flow generating portion is formed in the vicinity of the ink inlet 43a of the connecting portion 44 by a columnar crossing member 44a crossing the connecting portion 44. Since the flow of the ink liquid introduced into the ink supply path 43 during the purging process is partially blocked by the cross member 44a, a Karman vortex is generated, and the ink flow in the ink supply path 43 is reduced. It becomes turbulent. As described above, since the ink flow in the ink supply path 43 becomes turbulent, the ink flow velocity near the inner surface of the ink supply path 43 becomes larger than when the ink flow is laminar, and The microbubbles adhering to the inner surface are separated from the inner surface by the ink flow, and are easily discharged together with the ink liquid.

The turbulence generating section provided in the connecting section 44 is
In addition to the cross member 44a as described above, FIG.
As shown in (b), it can also be constituted by a pair of spiral projections 44b spirally projecting from the inner surface of the connecting portion 44. When the turbulent flow generating section is configured by such a spiral protrusion 44b, the ink flow in the ink supply path 43 during the purge process becomes a spiral vortex, and the ink supply path is compared with a case where the ink flow is merely a turbulent flow. A fast vortex flows along the inner surface of the ink supply passage 43 to reach the enlarged portion 45 from the connection portion 44 satisfactorily, thereby further improving the discharge property of the microbubbles attached to the inner surface of the ink supply passage 43.

In particular, in the case where the ink supply path 43 is formed so as to extend substantially vertically downward from the ink supply source to the ink jet head, when the shape of the spiral projection 44b is such that the vortex direction is used in the northern hemisphere, When used counterclockwise or in the southern hemisphere, by setting it clockwise, the Coriolis force works effectively and an effective eddy current can be generated.

As shown in FIG. 5, the enlarged portion 45 has an inner surface on the side of the connection portion 44 on the side of the injection channel 33.
And a first curved surface 45a which is tapered toward the end of the row and is curved so as to protrude inward. A second curved surface 45b that is curved so as to protrude outward. In other words, as described above, the connection portion 44 and the ink-jet head 31 side inward each other with respect to the substantially linear tapered surface substantially connecting the end of the connection portion 44 on the side of the ink-jet head 31 to the end of the row of the ejection channels 33. Projecting first curved surface 45
a, a shape with a second curved surface 45b protruding outward. By making the whole a gentle taper shape, turbulence and eddy current can easily reach the end along the inner surface of the enlarged portion 45.

The ink-jet head 31 is bent so that the second curved surface 45b of the enlarged portion 45 projects outward.
Is steeply connected to the other end surface of the ink jet head 31, the ink liquid flows from almost above into the corner formed by the second curved surface 45b and the other end surface of the inkjet head 31, and the air bubbles remaining in that portion Can be made very small.
Even if the bubble grows, the second curved surface 45b is curved so as to protrude outward as described above, so that a certain depth h is secured above the corner portion. Even if the air bubbles float on and adhere to the second curved surface 45b and grow, the grown air bubbles are not
It takes some time to reach the ink supply port 33a.

Further, since the second curved surface 45b of the enlarged portion 45 forming the corner portion is steep with respect to the other end surface of the ink jet head 31, the corner portion cannot be discharged by the purging process. Even when the microbubbles remain and grow, the bubbles easily float to the connection portion 44 side due to buoyancy, so that the bubbles are taken into the injection channel 33 within a short time after performing the purge process. There is no.

Further, due to the presence of the second curved surface 45b which is curved so as to protrude outward, the volume of the enlarged portion 45 is increased to some extent, and the bubbles grown in the central portion of the enlarged portion 45 It takes a certain amount of time before it comes into contact with the ink supply port 33a and is taken into the ejection channel 33.

As described above, by bending the inner surface of the enlarged portion 45 so that the side of the ink jet head 31 protrudes outward, bubbles remaining in the enlarged portion 45 grow and the ejection channels 33 of the ink jet head 31 are grown. Since the time until the ink liquid is taken in becomes longer, the time from when the purge process is performed to when the ink liquid is not discharged can be extended. Therefore, it is not necessary to frequently perform the purging process requiring several minutes of processing time, and the inkjet recording apparatus 1 can be used in a comfortable environment.

In the above-described embodiment, the turbulence generating portion is formed by the cross member 44a and the spiral projection 44b. However, the turbulence generating portion is not necessarily limited to such a shape. It is also possible to form a turbulent flow generating section by providing a spiral groove, a rapidly expanding section, a rapidly reducing section, or the like.

The above-described ink jet recording apparatus 1
Then, the nozzle plate 34 of the inkjet head 31
Although the purging process is performed by the ink suction device 21 that suctions from the side, it is not always necessary to perform the purging process by such a suction unit, and the ink pushing unit that pushes a new ink liquid from the ink cartridge side to the inkjet head side. Purge processing may be performed.

[0039]

In the ink jet recording apparatus according to any one of the first to fifth aspects of the present invention, the ink flow in the manifold becomes turbulent during the purging process, so that the ink flow velocity near the inner surface of the ink supply path increases. Accordingly, the microbubbles attached to the inner surface of the ink supply path can be efficiently discharged to the outside together with the ink.

In particular, when the turbulent flow generating portion is formed by a spiral projection projecting spirally from the inner surface of the connection portion of the ink supply path as in the ink jet recording apparatus according to the third aspect of the present invention, the spiral vortex is generated. As a result, a high ink flow velocity is formed along the inner surface of the ink supply path, and the microbubbles attached to the inner surface of the ink supply path can be more efficiently discharged to the outside together with the ink.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of an ink jet recording apparatus according to the present invention.

FIG. 2 is a partial sectional view showing the ink jet recording apparatus according to the first embodiment;

FIG. 3 is a perspective view showing a manifold used in the above-described ink jet recording apparatus.

FIG. 4 is a bottom view showing the manifold.

FIG. 5 is a sectional view taken along line XX of FIG. 4;

FIG. 6 is a sectional view taken along line YY of FIG. 4;

FIG. 7 is an enlarged view showing a turbulent flow generator of the manifold.

FIG. 8 is an enlarged view showing a turbulence generating section of a manifold according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink jet recording apparatus 21 Ink suction apparatus 30 Head unit 31 Ink jet head 32 Actuator 33 Injection channel 34 Nozzle plate 40 Manifold 43 Ink supply path 44 Connection part 44a Crossing member 44b Spiral protrusion 45 Enlarged part 50 Ink cartridge

Claims (5)

[Claims] An ink jet head provided with a plurality of ink storage chambers for storing ink to be ejected arranged in an aligned state, and the ink jet head and an ink supply source are connected to each other to form a plurality of the aligned ink storage chambers. In the room,
An ink jet recording apparatus comprising: a manifold having an ink supply path for supplying ink from the ink supply source; wherein the ink supply path extends outward from the connection portion connected to the ink supply source, An enlarged portion surrounding the ink supply ports of the plurality of aligned ink storage chambers, wherein the connecting portion generates a turbulent flow that generates turbulent flow in the ink introduced into the ink supply path from the ink supply source. An ink jet recording apparatus characterized by comprising a unit. 2. The turbulence generating section is formed by a cross member that traverses the connecting section.
3. The ink jet recording apparatus according to claim 1. 3. The ink jet recording apparatus according to claim 1, wherein the turbulence generating section is formed by a spiral projection that spirally projects from an inner surface of the connection section. 4. The ink jet recording apparatus according to claim 2, wherein the ink supply path is formed to extend substantially vertically downward from the ink supply source to the ink jet head. 5. An ink-jet head provided with a plurality of ink storage chambers for storing ink to be ejected in an aligned state, and the ink-jet head and an ink supply source are connected to each other to form a plurality of the aligned ink storages. In the room,
A manifold having an ink supply path for supplying the ink of the ink supply source, detachably connected to a side opposite to the manifold of the inkjet head, and supplying the ink of the ink supply source to the plurality of ink storage chambers through the manifold; An ink jet recording apparatus comprising: a suction unit that fills the ink; wherein the ink supply path is connected to the ink supply source, and the ink in the plurality of aligned ink storage chambers is extended outward from the connection part. An enlargement portion surrounding the supply port, and the connection portion is provided with a turbulence generation portion that generates turbulence in ink introduced from the ink supply source into the ink supply path by suction by the suction portion. An ink jet recording apparatus comprising: